void palette_device::configure_tilemap_groups(tilemap_t &tmap, gfx_element &gfx, int transcolor)
{
int color;
assert(gfx.colors() <= TILEMAP_NUM_GROUPS);
// iterate over all colors in the tilemap
for (color = 0; color < gfx.colors(); color++)
tmap.set_transmask(color, transpen_mask(gfx, color, transcolor), 0);
}
UINT32 palette_device::transpen_mask(gfx_element &gfx, int color, int transcolor)
{
UINT32 entry = gfx.colorbase() + (color % gfx.colors()) * gfx.granularity();
// make sure we are in range
assert(entry < m_indirect_pens.size());
assert(gfx.depth() <= 32);
// either gfx->color_depth entries or as many as we can get up until the end
int count = MIN(gfx.depth(), m_indirect_pens.size() - entry);
// set a bit anywhere the transcolor matches
UINT32 mask = 0;
for (int bit = 0; bit < count; bit++)
if (m_indirect_pens[entry++] == transcolor)
mask |= 1 << bit;
// return the final mask
return mask;
}